Career
Kumai joined Hello! Project in 2002 after passing the Hello! Project Kids audition. Hello! Project Kids Berryz Kobo (2004–2015) H.P. All Stars (2004) Guardians 4 (2009–2010) Hello! Project Mobekimasu (2011) Radio Berryz Kobo Kiritsu! Rei! Chakuseki! (Berryz工房 起立!礼!着席!) (2005-2003-30 – 2009-2003-31) Tsuukai! Berryz Okoku (July 3, 2009 - March 30, 2012) (Company-host: Sugaya Risako and Natsuyaki Miyabi) Internet Hello Pro Video Chat (Hello! Project on Flets) (2005-2008-08).